503 LOW-GRADE INTRAMEDULLARY CARTILAGE TUMORS: A REASSESSMENT OF DIAGNOSIS AND TREATMENT.

Background Benign and malignant cartilage-based neoplasms are known as enchondroma and chondrosarcoma, respectively. Enchondromas are usually asymptomatic and do not require treatment other than periodic clinical follow-up. Clinical behavior of chondrosarcoma ranges significantly, from high-grade lesions with a high rate of metastasis and mortality to low-grade lesions that tend only to be aggressive locally. Preoperative differentiation of enchondroma and low-grade chondrosarcoma relies upon tumor imaging, but a reliable clinical algorithm does not exist. Histologic examination of these tumors similarly fails to differentiate these tumors without correlation to imaging. Further exacerbating this problem, many institutions treat low-grade chondrosarcoma with en bloc resection, a highly morbid procedure that may not be warranted. Study Design and Methods Clinical, imaging, and treatment data from 250 patients with enchondroma and conventional chondrosarcoma were reviewed with the two-fold purpose of (1) defining a clinical algorithm and (2) determining whether intralesional curettage is adequate treatment for low-grade chondrosarcoma. To assess the potential of immunohistochemistry as a marker of malignancy, an equal number (n = 100) of enchondroma and chondrosarcoma core samples were assayed for a variety of suspected malignant markers. Results Among enchondromas, 42% were treated surgically due to uncertainty of malignancy preoperatively. Pain was not a statistically significant indicator of malignancy (p = .14). There were no recurrent enchondromas (n = 74). The recurrence rate among low-grade chondrosarcomas treated with curretage and cryotherapy in the appendicular skeleton was 8% (1/18) and 43% (3/7) in the axial skeleton. The recurrence rate for resected tumors was 14% (1/7) in the appendicular skeleton and 25% (2/8) in the axial skeleton. Conclusion A clinical algorithm consistently applied to intramedullary cartilage tumors has the potential to significantly decrease the number unnecessary surgical procedures. Furthermore, low-grade chondrosarcoma in the appendicular skeleton can be treated with curretage and cryotherapy to improve long-term functional outcome without increasing the risk of local recurrence relative to en bloc resection.